全文获取类型
收费全文 | 46774篇 |
免费 | 3854篇 |
国内免费 | 92篇 |
专业分类
耳鼻咽喉 | 499篇 |
儿科学 | 1905篇 |
妇产科学 | 1555篇 |
基础医学 | 6029篇 |
口腔科学 | 569篇 |
临床医学 | 5426篇 |
内科学 | 8830篇 |
皮肤病学 | 894篇 |
神经病学 | 5248篇 |
特种医学 | 1164篇 |
外国民族医学 | 2篇 |
外科学 | 5131篇 |
综合类 | 459篇 |
现状与发展 | 1篇 |
一般理论 | 77篇 |
预防医学 | 5894篇 |
眼科学 | 859篇 |
药学 | 2841篇 |
中国医学 | 39篇 |
肿瘤学 | 3298篇 |
出版年
2023年 | 639篇 |
2022年 | 1032篇 |
2021年 | 2019篇 |
2020年 | 1223篇 |
2019年 | 1766篇 |
2018年 | 1990篇 |
2017年 | 1361篇 |
2016年 | 1546篇 |
2015年 | 1607篇 |
2014年 | 2117篇 |
2013年 | 2684篇 |
2012年 | 3883篇 |
2011年 | 3792篇 |
2010年 | 1924篇 |
2009年 | 1647篇 |
2008年 | 2570篇 |
2007年 | 2698篇 |
2006年 | 2356篇 |
2005年 | 2164篇 |
2004年 | 1878篇 |
2003年 | 1622篇 |
2002年 | 1450篇 |
2001年 | 408篇 |
2000年 | 421篇 |
1999年 | 451篇 |
1998年 | 326篇 |
1997年 | 215篇 |
1996年 | 188篇 |
1995年 | 187篇 |
1994年 | 175篇 |
1993年 | 164篇 |
1992年 | 266篇 |
1991年 | 270篇 |
1990年 | 265篇 |
1989年 | 228篇 |
1988年 | 206篇 |
1987年 | 200篇 |
1986年 | 223篇 |
1985年 | 228篇 |
1984年 | 165篇 |
1983年 | 154篇 |
1982年 | 116篇 |
1981年 | 109篇 |
1979年 | 170篇 |
1978年 | 120篇 |
1977年 | 118篇 |
1975年 | 109篇 |
1974年 | 137篇 |
1973年 | 114篇 |
1972年 | 109篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Dorit Naot Usha Bava Brya Matthews Karen E Callon Gregory D Gamble Michael Black Sarah Song Rocco P Pitto Tim Cundy Jill Cornish Ian R Reid 《Journal of bone and mineral research》2007,22(2):298-309
Paget's disease is a focal condition of bone. To study changes in cells within pagetic lesions, we cultured osteoblasts and stromal cells from 22 patients and compared gene expression in these cells to cells from healthy bone. We identified several differentially regulated genes, and we suggest that these changes could lead to the formation of the lesions. INTRODUCTION: Paget's disease is a focal condition of bone of unknown cause. Although it is regarded as primarily an osteoclast disorder, the tight coupling of the activity of osteoclasts and osteoblasts suggests that the osteoblast could play a key role in its pathogenesis. The aim of the study was to identify possible changes in pagetic osteoblasts and stromal cells that might contribute to the development of pagetic lesions. MATERIALS AND METHODS: Candidate genes were identified based on known bone cell regulators, supplemented with microarray analysis. Gene expression was determined by real-time PCR in primary cultures of osteoblasts and bone marrow stromal cells from pagetic patients and control subjects. Concentrations of secreted proteins were determined by ELISA. RESULTS: Dickkopf1 mRNA and protein levels were increased in both pagetic osteoblast and stromal cell cultures, and interleukin (IL)-1 and IL-6 were overexpressed in pagetic osteoblasts. These changes parallel recent findings in myeloma bone disease, which shares some clinical similarities with Paget's disease. Alkaline phosphatase was overexpressed, and bone sialoprotein and osteocalcin were underexpressed in pagetic osteoblasts, consistent with their circulating levels in pagetic patients. It is hypothesized that overexpression of Dickkopf1, IL-1, and IL-6 would result in stimulation of osteoclast proliferation and inhibition of osteoblast growth, leading to the development of the characteristic lytic bone lesions. By stimulating osteoblast differentiation, Dickkopf1 and IL-6 may also promote mineralization, leading to the conversion of lytic lesions to sclerotic. CONCLUSIONS: These findings suggest that dysregulated gene expression in pagetic osteoblasts could cause the changes in bone cell number and function characteristic of Paget's disease. 相似文献
63.
Deborah A Cahn-Weiner Sarah Tomaszewski Farias Laura Julian Danielle J Harvey Joel H Kramer Bruce R Reed Dan Mungas Margaret Wetzel Helena Chui 《Journal of the International Neuropsychological Society》2007,13(5):747-757
Impaired ability to conduct daily activities is a diagnostic criterion for dementia and a determinant of healthcare services utilization and caregiver burden. What predicts decline in instrumental activities of daily living (IADLs) is not well understood. This study examined measures of episodic memory, executive function, and MRI brain volumes in relation to baseline IADLs and as predictors of rate of IADL change. Participants were 124 elderly persons with cognitive function between normal and moderate dementia both with and without significant small vessel cerebrovascular disease. Random effects modeling showed that baseline memory and executive function (EXEC) were associated with baseline IADL scores, but only EXEC was independently associated with rate of change in IADLs. Whereas hippocampal and cortical gray matter volumes were significantly associated with baseline IADL scores, only hippocampal volume was associated with IADL change. In a model including cognitive and neuroimaging predictors, only EXEC independently predicted rate of decline in IADL scores. These findings indicate that greater executive dysfunction at initial assessment is associated with more rapid decline in IADLs. Perhaps executive function is particularly important with respect to maintaining IADLs. Alternatively, executive dysfunction may be a sentinel event indicating widespread cortical involvement and poor prognosis. 相似文献
64.
CPT Tony Pierson Jeffrey A. Niezgoda MD LT Sarah Learmonth CPT Dennis Blunt LTC Kevin McNabb 《Wound repair and regeneration》2005,13(2):1-2
Abstract Brooke Army Medical Center isolated 25 highly antibiotic‐resistant Acinetobacter ssp . (primarily A. baumannii ) from wounded soldiers returning from Iraq. Concern about effective treatment of these organisms led our institution to begin investigating low‐frequency ultrasound (LFU) as a method of increasing the effectiveness of antibiotics on A.baumannii in wound management. Studies have suggested that LFU applied in conjunction with antibiotics may increase their overall effectiveness. We hypothesize that combining antibiotics with LFU may be an effective method of wound management and that this combination may be synergistic in its overall effect. In this initial work, we wanted to determine if sonocation would have an effect on our organism of interest, A. baumannii . We selected several organisms, both gram positive and gram negative, that have been shown to be killed by sonocation ( E. coli, S. aureus , and S. pyogenes ) and added three highly resistant A. baumannii isolates. Bacterial death was measured by both colony counts after 24 hours of growth and acridine orange staining using a standard protocol.
Colony counts were significantly reduced by sonocation. Furthermore, A.'baumannii colony counts were also greatly reduced by sonocation. Actual cell destruction was also visualized using acridine orange staining. Our data support the assertion that sonocation has an antibacterial effect on some bacteria, including A. baumannii . Our next step is to add antimicrobial agents and determine if their effectiveness can be increased by sonocation. 相似文献
Colony counts were significantly reduced by sonocation. Furthermore, A.'baumannii colony counts were also greatly reduced by sonocation. Actual cell destruction was also visualized using acridine orange staining. Our data support the assertion that sonocation has an antibacterial effect on some bacteria, including A. baumannii . Our next step is to add antimicrobial agents and determine if their effectiveness can be increased by sonocation. 相似文献
65.
66.
Jean-Pierre Chanoine MD PhD Sarah Hampl MD FAAP Craig Jensen MD Mark Boldrin MS Jonathan Hauptman MD 李呈亿 《美国医学会杂志》2006,25(1):34-43
背景:儿童和青少年超重和肥胖正迅速增加。在该人群,单纯行为疗法减肥及维持体重下降的效果有限,但是对药物治疗尚未进行广泛的研究。
目的:确定奥利州他(Orlistat)在青少年体重治疗方面的效果及其安个性。
设计、地点和病例:于美国和加拿大32个中心、539例肥胖青少年(12—16岁;体重指数[body mass index,BMI]在第95百分化之上≥2单位)进行的多ln0、54剧(2000年8月至2002年10月)随机双盲研究。
干预:给予奥利司他(n=357)或安慰剂(n=182)120mg,每口3次,持续1年;加适度低热卡饮食(脂肪占30%)、运动和行为治疗。
主要观察指标:BMI变化;二级指标包括腰围和髋用、体重下降、脂质测量以及机体对口服葡萄糖的血糖和胰岛素反心。
结果:至12周时,两组BMI均有下降;此后,奥利司他组体重维持稳定而安慰剂组则超过基线。研究结束时,奥利司他组BMI下降0.55。而安慰剂组则增加0.31(P=0.001)。与安慰剂组的15.7%相比,奥利司他组26.5%的病例BMI下降≥5%(P=0.005);BMI下降≥10%者分别为4.5%和13.3%(P=0.002)。在研究结束时,奥利司他组体重增加0.53kg,安慰剂组增加3.14kg(P〈0.001)。双能X线吸收测量娃示,这种差异可用脂肪体再的变化解释。奥利司他组腰围下降,安慰剂组腰围上升(-1.33cm比+0.12cm;P〈0.05)。奥利司他组发生轻至中度胃肠道不良事件者为9%-50%,安慰剂组为1%~13%。
结论:与安慰剂比较,奥利司他与饮食、运动和行为改善联合可显著改善肥胖青少年体重的治疗。在这个青少年人群,连续使用奥利司他1年并无重要安全问题,尽管奥利司他组胃肠道不良事件较为常见。 相似文献
67.
David M. Rice Marvin Rosen Gregg M. Macmann 《Journal of developmental and physical disabilities》1991,3(1):59-67
A self-administered questionnaire was developed to examine two dimensions of staff attitudes: (a) the perceived importance of skills that direct-care workers who are asked to teach their clients, and (b) staff expectations that clients will show improvement in these areas. The relationship between importance/ expectancy ratings and self-reported teaching activity was studied in a sample of 32 direct-care workers at a residential facility for adults with developmental disabilities. In general, direct-care workers reported that they were most frequently engaged in escorting clients, watching and teaching clients during recreational activities, and dealing with client's emotional/behavioral outbursts. Improtance/expectancy ratings were correlated significantly with the education level of respondents, but not with self-reported teaching activity. 相似文献
68.
69.
70.